Today's non-linear video editors emerged from conventional editing methods such as film cutting and linear dub-editing using video players. These tools are well suited to scenarios where the desired result is a single, high-quality video production. It is not possible, however, to view multiple editing alternatives of a video production quickly using these tools, which is an impediment particularly to novice video editors. A video production novice therefore is forced either to “make do” with whatever the novice may create quickly or to spend a lot of time exploring alternatives.
A number of trends are creating a need for a radically different video production tool. One such trend is seen in the rapid growth of the amount of video material being shot or recorded, particularly video material shot by non-professionals. Technological developments or breakthroughs resulting in products such as Digital Video (DV) cameras mean that more and more video material are shot or recorded in digital format and of professional or near-professional technical quality. However, the cost of editing this type of video material using traditional tools is prohibitive in many cases.
Another trend is seen in the extension of the video material viewing paradigm beyond familiar broadcast and VCR paradigms. Viewers want increasing control over video material being watched, for how long, in what sequence, etc. This trend is particularly true for non-fiction video material in educational and professional environments. This trend also implies that there is a growing need to make bodies of video material available in multiple forms, for example, in video productions of different lengths, with different emphases, aimed at different audience demographics, etc.
Yet another trend is seen in the exponentially increasing availability of the amount of video material available in digital format and on the Internet. This trend drives a growing need for effective description of video material by using descriptors, so that video material appropriate to a particular purpose may be retrieved from a large body of available video material through the use of descriptors. There is great interest in the area of video material description today driving standardization efforts such as the Moving Pictures Experts Group's (MPEG) effort in relation to an MPEG-7 standard. However, a major challenge faces such efforts, and this challenge arises from two complementary facts. Firstly, descriptors automatically extracted from video material using signal analysis of the video material and therefore associated with such video material tend to lack semantic power because these descriptors are too low-level to be useful to and meaningful in the ordinary context so as to be understood by most users. Secondly, although semantically powerful descriptors may be associated with video material by being manually entered using a video production tool, this process is tedious and time-consuming and therefore the process may not be cost-effective in many applications.
Hence, there is clearly a need for a video production tool that addresses at least one of the foregoing trends.